A switching regulator such as a voltage step-up converter has a voltage step-up chopper circuit in which a switching element is coupled to a series node of an inductor and a diode. When the switching element is turned on, energy is accumulated in the inductor by a current supplied from a rectifier circuit. Also, when the switching element is turned off, a smoothing capacitance is charged by the energy accumulated in the inductor through the diode. A voltage step-up operation is performed by repeating this operational cycle. In this regard, a PFC controller controls an-on duty of the switching element, for example, by comparing a correlation value between a divided voltage of the voltage obtained in the smoothing capacitance and the amount of an AC input voltage rectified by the rectifier circuit with a triangular wave formed in its internal oscillator, and the PFC controller keeps the stepped-up voltage at a constant level and performs a control to allow the AC input current to be close to a sine wave.
Patent Documents 1 and 2 disclose a technology for an interleaved switching regulator which comprises plural voltage step-up chopper circuits in which switch control is performed by shifting phases of switching elements of respective voltage step-up chopper circuits. In Patent Document 1, a pair of capacitance elements which are charged and discharged complementarily for timing generation to shift phases. In Patent Document 2, when generating timing for shifting the phases, a triangular-wave signal and a corresponding threshold value are used.
[Patent Document 1] Japanese Unexamined Patent Publication No. Hei 10 (1998)-146049
[Patent Document 2] Japanese Unexamined Patent Publication No. 2001-178122